Which AI model to use for writing, coding, research and summaries

"Which AI is the best?" has no lasting answer. Providers release new versions every few months, rankings move, and a model that writes beautifully may be slow at arithmetic or unable to read a PDF. A more useful question is narrower: which model is best for this task, for you, right now?

This guide gives you a quick way to answer it. Start from what the task needs, shortlist models that have that capability, and confirm with a short test on your own material. In Cortex AI, models from OpenAI (GPT), Anthropic (Claude), Google (Gemini), DeepSeek, xAI (Grok) and Alibaba Cloud (Qwen) sit in one model picker, so shortlisting and switching take seconds.

Start from what the task needs

Most everyday tasks depend on one or two capabilities more than on the name of the model. Ask yourself four questions before you pick.

• Does it need to be fast or deep? Rewriting a sentence, translating a message or answering a quick question rewards speed. Planning, maths, logic and tricky bugs reward a model that reasons step by step, even if it takes longer.
• Does it depend on current information? Anything about prices, news, releases or schedules needs a model that can search the web, because built-in knowledge stops at the training cut-off.
• Does it involve a file or an image? Then the model must accept attachments; not every model reads images and PDFs.
• What does a good result look like? A cold email, working code and a faithful summary are judged differently. Decide your criteria before you compare.

A starting map of tasks and capabilities

• Writing and editing: emails, posts, product copy and stories. Start with models marked Creative, then set the tone (professional, casual, academic or creative) so you are not fighting the default voice.
• Coding: writing functions, explaining errors, reviewing changes. Start with Coding models; for a bug whose cause is unclear, try a Deep Thinking model as well.
• Research and current events: start with a model that supports Web Search, ask for its sources and open them.
• Summarising documents and images: use a model with Vision support and attach the file instead of pasting text.
• Maths, logic and planning: Deep Thinking models work through problems step by step, which also makes their mistakes easier to spot.
• Quick questions and translations: a Fast model keeps the conversation snappy; move to a larger model only if the quality falls short.
• Other languages: quality varies by language and by model, so test in the language you will actually use.

Find and confirm your model in Cortex AI

1. Filter the model picker by capability. Open the model picker and tap a filter such as Fast, Deep Thinking, Coding, Creative, Web Search or Vision. Each model also shows a one-line description of what it is good at.
2. Shortlist two. Pick two models that fit the task, ideally from different providers, since they often fail in different ways.
3. Test on a real example. Use a task you actually have, not a riddle. Send it to both shortlisted models at once in compare mode and read both answers in full before judging.
4. Vote and note the winner. Pick the better answer. Cortex AI tracks your votes, so over time you can see which models you choose for which kind of work.
5. Switch when the task changes. A new need does not require a new chat. Change the model mid-conversation with one tap, for example drafting with one model and asking another to check the facts or the code.

Keep your choices up to date

Treat your picks as defaults, not verdicts. When a provider releases a new version, or when your usual model starts missing on a kind of task, rerun the same test prompts. Keeping three or four saved prompts per task (a real email, a real bug, a real article to summarise) turns that into a five-minute job, and the prompt library's templates for coding, writing, translation and analysis are a good starting point for building the set.

Caveats

Capability filters describe what a model is designed for, not a guarantee of quality on your task, and faster models usually trade some depth for speed. The models and features available to you, including compare mode, web search and file attachments, depend on your plan, and the app shows which ones yours includes. Whichever model you choose, its answers can be wrong or out of date, so verify facts, figures and code before you rely on them.

Model and company names are trademarks of their respective owners and are used here only to identify the models available in the app. Cortex AI is an independent app and is not affiliated with or endorsed by these companies.